# Speeds of travel in different media

### Vibrations in solids, liquids and space

Vibrations can travel through any medium, so long as there are enough particles in each cubic metre so that the to-and-fro motion of one block of particles passes on to their neighbours. If the particles are too far apart then there are not enough collisions for the vibrations to pass from one block to the next.

The particles in solids, liquids and gases are arranged and connected in different ways. So you can expect differences in the speed at which the vibrations travel through solids, liquids or gases. How far the vibrations travel also changes on how the particles are arranged and connected.

Both speed and range depend on how the vibrations pass on from one block of particles to the next.

Sounds travel faster and further in solids. So put your ear to the ground to find out what's happened sooner.

In liquids sounds also travel over great distances at considerable speed. You can listen in to whales as they communicate with one another.

Some examples of the speed at which the vibrations travel: air: 340 m/s water: 1500 m/s steel: 6000 m/s

In deep space, there are only about 3 particles of hydrogen per cubic metre and this is not enough to sustain a sound. The booms of space movies are made up. You cannot hear explosions in outer space.

In space, no-one can hear you scream

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